Programme for Physiology and Neurobiology, Department of Molecular Biosciences, University of Oslo, Norway; Department of Biological Sciences, University of Alaska Anchorage, AK, USA.
Programme for Physiology and Neurobiology, Department of Molecular Biosciences, University of Oslo, Norway; Department of Biological Sciences, University of Alaska Anchorage, AK, USA.
Comp Biochem Physiol Part D Genomics Proteomics. 2019 Jun;30:55-70. doi: 10.1016/j.cbd.2018.12.010. Epub 2019 Feb 13.
We investigated if transcriptional responses are consistent with the arrest of synaptic activity in the anoxic turtle (Trachemys scripta) brain. Thirty-nine genes of key receptors, transporters, enzymes and regulatory proteins of inhibitory and excitatory neurotransmission were partially cloned and their expression in telencephalon of 21 °C- and 5 °C-acclimated normoxic, anoxic (24 h at 21 °C; 1 and 14 days at 5 °C) and reoxygenated (24 h at 21 °C; 13 days at 5 °C) turtles quantified by real-time RT-PCR. Gene expression was largely sustained with anoxia at 21 °C and 5 °C. However, the changes in gene expression that did occur were congruous with the decline in glutamatergic activity and the increase in GABAergic activity observed at cellular and whole organism levels. Moreover, at 21 °C, the alterations in gene expression with anoxia induced a distinct gene expression pattern compared to normoxia and reoxygenation. Strikingly, acclimation from 21 °C to 5 °C in normoxia effectuated substantial transcriptional responses. Most prominently, 56% of the excitatory neurotransmission genes were down-regulated, including most of the ones encoding the subunits composing excitatory N-methyl-d-aspartate (NMDA) and 3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) glutamate receptors. By contrast, only 26% of the inhibitory neurotransmission genes were down-regulated. Consequently, the gene expression pattern of 5 °C normoxic turtles was statistically distinct compared to that of 21 °C normoxic turtles. Overall, this study highlights that key transcriptional responses are consonant with the synaptic arrest that occurs in the anoxic turtle brain. In addition, the findings reveal that transcriptional remodelling induced by decreased temperature may serve to precondition the turtle brain for winter anoxia.
我们研究了转录反应是否与缺氧海龟（Trachemys scripta）大脑中突触活动的抑制一致。我们部分克隆了 39 个关键受体、转运蛋白、酶和兴奋性及抑制性神经递质的调节蛋白的基因，并通过实时 RT-PCR 定量检测了其在 21°C 和 5°C 驯化的正常氧、缺氧（21°C 24 小时；5°C 1 天和 14 天）和复氧（21°C 24 小时；5°C 13 天）海龟端脑的表达。21°C 和 5°C 缺氧时，基因表达基本维持不变。然而，确实发生的基因表达变化与细胞和整体水平上观察到的谷氨酸能活性下降和 GABA 能活性增加一致。此外，在 21°C 时，缺氧引起的基因表达变化与正常氧和复氧相比，诱导了一种独特的基因表达模式。值得注意的是，21°C 正常氧下的 5°C 驯化导致了大量的转录反应。最显著的是，90%的兴奋性神经递质基因下调，包括构成兴奋性 N-甲基-D-天冬氨酸（NMDA）和 3-羟基-5-甲基-4-异恶唑丙酸（AMPA）谷氨酸受体的大多数亚基编码基因。相比之下，只有 26%的抑制性神经递质基因下调。因此，5°C 正常氧海龟的基因表达模式与 21°C 正常氧海龟的基因表达模式在统计学上明显不同。总的来说，这项研究强调了关键的转录反应与缺氧海龟大脑中发生的突触抑制是一致的。此外，研究结果表明，低温诱导的转录重编程可能使海龟大脑为冬季缺氧做好准备。
